Enhanced and modulated optical response of GaSe by coupling with resonant linear Bragg gratings

Abstract

The extensive application of GaSe in optoelectronic devices has generated great enthusiasm for the study of their fundamental properties. Despite its high quantum yield and superb nonlinearity, the intrinsic out-of-plane transition dipole of excitons in GaSe leads mainly to in-plane photoluminescence (PL) emission, which results in poor detection efficiency normal to the sample surface. Here, we demonstrate a practical strategy for boosting and modulating the PL of GaSe by transferring it onto dielectric linear Bragg gratings (LBGs), achieving a significant 42-fold enhancement in PL at room temperature. Furthermore, the use of the LBG results in strong linear polarization of the original isotropic PL emission. In addition, temperature-dependent experiments indicate that the LBG results in maximum modulation of PL at 605 nm, an up to 150-fold increase. Through this work, we provide a facile method to enhance the exciton recombination and light outcoupling efficiency of GaSe, which can be further applied to other van der Waals layered materials with out-of-plane optical dipole transition for enhanced optoelectronic device performance.